‘蜜世界’洋香瓜做嫁接栽培，以生產高品質果實及解決設施中連作障礙，並增加於低溫下耐寒性，本研究以 ‘蜜世界’ 洋香瓜作為接穗，嫁接於越瓜‘黑皮’、‘銀華’與‘青皮’砧木和南瓜‘壯士’、‘共榮’與‘新土佐’砧木，採用頂劈接、貼接與靠接三種方式，嫁接癒合後調查成活率，並定植於三吋盆中調查栽培兩週之生長情形。
嫁接成活率以越瓜砧木顯著優於南瓜，越瓜砧木不同品種之間沒有顯著差異，頂劈接和貼接之間沒有顯著差異，較靠接之成活率高。定植後7天及14天以嫁接處理顯著促進植株的營養生長，頂劈接嫁接苗中，除了南瓜‘共榮’砧木嫁接苗，其他組合顯著促進接穗長、葉片數、葉面積與地上部鮮乾重累積。貼接嫁接苗中，越瓜‘青皮’與南瓜‘壯士’砧木顯著增加接穗長與地上部鮮乾重，南瓜‘共榮’砧木嫁接苗之生長情形亦不佳，推薦越瓜‘青皮’、南瓜‘壯士’和‘新土佐’作為砧木，以頂劈接為主要的嫁接方式。
‘蜜世界’洋香瓜頂劈接苗栽培於田間，嫁接均顯著提早始花期促進果實產量，但糖度於處理間沒有顯著差異；‘蜜世界’洋香瓜嫁接苗以5 L塑膠袋栽培於簡易遮雨棚，越瓜‘青皮’砧木嫁接苗之果實重量顯著優於其他處理組，糖度於處理間沒有顯著差異。石蠟切片觀察嫁接部位癒合情形結果表示所有頂劈接苗於嫁接後第3天均癒合良好沒有分離的現象，並有壞死層的出現，處理間不影響嫁接苗吸收壞死層的速度，於嫁接後第12天，癒合處有觀察到新生維管束，嫁接處理於此時壞死層幾乎完全消失，唯南瓜‘壯士’砧木苗有較零星的壞死層組織存在。
洋香瓜頂劈接苗以連作介質栽培結果顯示其顯著抑制嫁接苗與自根苗生長，但是嫁接苗之營養生長仍顯著較自根苗佳，有較佳的葉面積與鮮乾重累積。以HPLC分析收穫後之介質酚酸結果表示，自根苗介質以沒食子酸和香草酸為主，其他處理以沒食子酸與間羥基苯甲酸為主，總酚含量以南瓜‘新土佐’顯著最高，自根苗與‘青皮’越瓜之間沒有顯著差異，南瓜‘壯士’之總酚含量最低。洋香瓜頂劈接苗處理沒食子酸結果顯示處理不影響嫁接苗生長，但顯著影響自根苗生長，其地上部鮮乾重顯著減少。
洋香瓜頂接苗於低溫13℃下生長結果顯示嫁接苗與自根苗均因低溫而生長受到抑制，嫁接苗比自根苗有顯著較佳之鮮乾重。低溫處理7天後嫁接苗與自根苗之抗氧化酵素活性均有被促進，越瓜‘青皮’砧木嫁接苗有顯著較低的MDA含量，其電解質滲漏率與南瓜‘壯士’砧木苗沒有顯著差異較其他處理低。In order to enhance growth potential, produce high-quality fruit, overcome continuous cropping problems in greenhouses, and obtain plants with a better tolerance to cold environments, grafting techniques were used for melons. ‘Honey World’ Melon was used as the scion to graft by top cleft, splice or tongue approaches, and oriental pickling melons ‘Hei Pi’, ‘Yin Hua’ and ‘Qing Pi’, in addition to squash ‘Zhuang Shi’, ‘Gong Rong’ and ‘Xin Tu Zuo’, were used as rootstocks in this study. The survival rate of the grafted seedlings and their growth during the two weeks after transplanting into 3-inches pots were investigated.
The survival rate of the grafted seedlings with oriental pickling melon rootstocks was higher than those with squash rootstocks. No difference in grafted seedlings growth was seen between those grown using three different oriental pickling melons as rootstocks. Top cleft and splice graft approaches resulted in similar survival rates, which were higher than the rate obtained following tongue grafting. On date 7 and 14 after transplant, using the top cleft grafting method, the grafted seedlings with all rootstocks had significantly better plant growth than the controls (no grafting), including increase in scion stem length, number of leaves, leaf area, and above-ground fresh and dry weight. With splice grafting, grafted seedlings with oriental pickling melon ‘Qing Pi’ and squash ‘Zhuang Shi’ as their rootstocks had significantly improved scion stem length and greater above-ground fresh and dry weight, while grafted seedlings produced using squash ‘Gong Rong’ as the rootstock exhibited poor growth. The results demonstrated that top grafting is the best method, and oriental pickling melon ‘Hei Pi’ and squash ‘Zhuang Shi’ and ‘Xin Tu Zuo’ are recommended for use as rootstocks for melon grafting.
In the field study, the grafted plants exhibited significantly earlier flowering, and fruit production was promoted, while no difference in the fruit sugar content was noted between seedlings grown using different grafting techniques and different rootstocks. When plants were grown under a plastic rain shelter, the plants grafted on oriental pickling melon ‘Qing Pi’ had a significantly higher fruit weight, while containing the same high sugar content as plants grown under other treatments. Histological study of paraffin sections of the grafted junctional tissue showed that wounds were all bonding together tightly and had healed 3 days after grafting. In addition, necrotic layers were observed on the junction with all grafting methods, but these layers had almost disappeared by day 12 after grafting, and formation of vascular bundles was observed, with the exception that spotted necrotic layers were seen in the tissues of plants grafted on squash ‘Zhuang Shi’.
When the melon seedlings were cultured with medium that had been used for continuous cropping twice, the medium exerted a significant inhibitory effect on the growth of both grafted and un-grafted seedlings, while the growth of the grafted seedlings was still better than that of the un-grafted seedlings. The grafted seedlings had a larger leaf area and greater above-ground fresh and dry weights.
Using HPLC to analyze the phenolic compounds in the medium, the results showed that medium used for un-grafted melons mainly contained gallic acid and vanillic acid, and medium used for grafted melons mainly contained gallic acid and m-hydroxybenzoic acid. In terms of the level of total phenolic compounds, medium-cultured grafted melon produced using squash ‘Xin Tu Zuo’ as the rootstock had the highest content, followed by un-grafted plants and those that used oriental pickling melon ‘Qing Pi’ as the rootstock, which had similar levels of total phenolic compounds; melon produced using squash ‘Zhuang Shi’ as the rootstock had the lowest content.
The plant growth of both grafted and un-grafted seedlings was inhibited when melons were cultured in a low-temperature environment at 13℃ for 7 days, while the grafted seedlings had significantly greater fresh and dry weights. The activities of reactive oxygen species-scavenging enzymes were promoted by the low temperature in the grafted and un-grafted seedlings. Plants grown from seedlings produced using oriental pickling melon ‘Qing Pi’ as the rootstock had a significantly lower MDA content, and their electrolyte leakage rate was at a similar level to that of seedlings grown using squash ‘Zhuang Shi’ as the rootstock, which was significantly lower than that of seedlings produced using other rootstocks.